Rotary arm contactless switch



Aug. 15, 1961 N. BERMAN ROTARY ARM CONTACTLESS SWITCH 2 Sheets-Sheet 1Filed July 29, 1957 Q mh ww ww Q ww E w ww \w Q Q- mm vw E N O w Q 6% vvw NM 0 I N QM NM ow HQ WM NW 1 1 I wm N v wN bx vm United States Patent2,996,694 ROTARY ARM CONTACTLESS SWITCH Nelson Berman, New Hyde Park,N.Y., assignor, by mesne assignments, to United Aircraft Corporation,East Hartford, Conn, a corporation of Delaware Filed July 29, 1957, Ser.No. 674,735 3 Claims. (Cl. 336.120)

My invention relates to a rotary arm contactless switch and moreparticularly to a rotary arm contactless switch for sequentiallysampling voltage analogues of a number of respective physical variables.

It is often necessary or desirable to provide an indication at a centralstation of a number of physical variables measured at respective remotelocations. Various means are known in the prior art which provide avoltage analogue of a physical variable being measured. These voltageanalogues may readily be conducted to a central station at which theyare to be read. In the prior art rotary switches having interengageable,relatively movable brushes and contacts are known for sequentiallysampling a plurality of respective voltages applied to the switchcontacts. After a period in operation of these switches of the prior artthe brushes become worn and must be replaced. The contacts of theswitches, which are formed of a conducting material such as copper,become dirty in use and require frequent cleaning. If proper maintenanceis not given the switches of the prior art at relatively frequentintervals false indications will be provided by the switches. Further,the brushes and contacts of these switches of the prior art are likelyto become disarranged as a result of shock forces applied to the switch.

I have invented a rotary arm contactless switch for sequentiallysampling voltage analogues of a number of physical quantities beingmeasured. In my switch there is no direct physical engagement betweenthe moving and stationary members. My switch does not use the brushesand contacts of switches of the prior art. My switch is extremely ruggedand reliable. It requires very little maintenance even after a longperiod of time in operation.

One object of my invention is to provide a rotary arm contactless switchfor sequentially sampling voltage analogues of a number of physicalvariables being measured.

Another object of my invention is to provide a rotary arm contactlessswitch in which there is no direct physical contact between the movingand stationary switch elements.

A further object of my invention is to provide a rotary arm contactlessswitch which does not employ the relatively movable brushes and contactsof sampling switches of the prior art.

Yet another object of my invention is to provide a rotary armcontactless switch which is rugged and reliable.

A still further object of my invention is to provide a rotary armcontactless switch which requires little maintenance even after a longperiod of time in use.

Other and further objects of my invention will appear from the followingdescription:

In general my invention contemplates the provision of a rotary armcontactless switch for sampling a plurality of voltage analoguesincluding a number of respective primary windings carried by teethformed of magnetic material fixed on a stationary support. I impress therespective voltage analogues on the primary windings. A member movablewith respect to the stationary member supports a secondary winding. Themovable member is adapted to be moved to pass the secondary windingthrough the respective primary winding magnetic ice fields produced bythe voltage analogues. As the movable member moves the secondary windingthrough the primary winding fields, a plurality of respective voltageshaving magnitudes proportional to the physical variables are induced inthe secondary winding. My switch includes means carried by the movablemember for completing the primary winding flux paths.

In the accompanying drawings which form part of the instantspecification and which are to be read in conjunction therewith and inwhich like reference numerals indicate like parts in the various views:

FIGURE 1 is a sectional view of one form of my rotary arm contactlessswitch.

FIGURE 2 is a sectional view of the form of my contactless switch shownin FIGURE 1 taken along the line 22 of FIGURE 1 with parts removed.

FIGURE 3 is a development of a multiple form of my contactless switchwith parts shown in section.

Referring now more particularly to FIGURES 1 and 2 of the drawings, myrotary arm contactless switch includes a stationary ring 10 supported inthe switch housing I2 by any convenient means such as brackets I4 and16. I form ring 10 from a diamagnetic material such as plastic, or thelike, and provide the ring with a plurality of threaded bores 18 spacedaround the ring. A plurality of respective teeth 20 formed of magneticmaterial and screwed into the ring bores 18 carry a plurality ofrespective primary windings 22. Pairs of conductors 24 and 26 connectwindings 22 to devices (not shown) known in the art for producingrespective voltage analogues of physical quantities being measured. Itwill be appreciated that the voltage analogues generate respectivecurrents in windings 22 to produce fluxes in the teeth '20.

I mount a hub 28 by means of a key or the like 30 on a shaft 32rotatably supported in housing 12 by a bearing 34. An arm 36 formed onhub 28 carries a secondary winding 38 to which I connect respectiveconductors 4t) and 42. Winding 38 is positioned to pass through themagnetic fields of the respective primary windings 22 as shaft 32rotates. I form hub 28 with a radially extending arm 44 provided at itsend remote from hub 28 with a laterally extending portion 46. This arm44 with its portion 46 provides a path for the flux from the primarywinding adjacent which the secondary winding 38 is disposed at anyparticular time. It is to be understood that arm 36, hub 28 and arm 44are formed from a suitable magnetic material. As hub 28 rotates, winding38 sequentially passes through the respective fields of the teeth 20 togenerate respective voltages in winding 38. These generated voltages maybe conducted from conductors 40 and 42 by any convenient means known tothe art such, for example, as slip rings and brushes or a magneticcoupling. The current flowing through each of the respective windings 22is proportional to the voltage analogue applied to the winding. The fluxin each tooth is proportional to the winding current. The signal inducedin the secondary winding 38 as it passes a given tooth 20 isproportional to the field strength of the tooth fiux. It will be seenthat the voltage induced in secondary winding 38 as it passes by a tooth20 is proportional to the voltage analogue fed to the primary windingcarried by the tooth.

Referring now to FIGURE 3, I have shown a multiple form of my rotary armcontactless switch. This form includes a plurality of respective rings48, 50, 52, and 54 of nonmagnetic material each of which rings carries aplurality of spaced teeth 20 of magnetic material. Each tooth 20 carriesa winding 22. It is to be noted that the respective teeth of the rings48, 50, 52 and 54 are staggered with respect to each other. I providerespective Secondary windings 56, 58, 6t) and 62 adapted to be passedthrough the primary magnetic fields of the respective rings 48, 50, 52and 54. The windings 56, 58, 60 and 62 are carried by arms 36 fixed on acommon shaft 63 shown in phantom in FIGURE 3 rotatably supported in thefixed housing 65. An arm 44 having a portion 46 is associated with eachof the windings 56, '58, 60 and 62. Owing to the staggered arrangementof the magnetic teeth in the multiple form of my switch, a series ofspaced pulses equal to the total number of teeth will be produced. Iemploy respective conductors 64, 66 and 68 to connect secondary windings56, 58, and 62 in series. Respective conductors 70 and 72- connected towindings 56 and 62 carry the output signals of all the windings 56, 58,60 and 62 to the external circuit. Conductors 70 and 72 carry a seriesof spaced signals equal to the total number of teeth 20 in the multipleform of my switch.

In operation of the form of my invention shown in FIGURE 2, respectivepairs of conductors 24 and 26 impress voltage analogues of the physicalvariables to be measured on the primary windings 22. These voltageanalogues may be direct current or alternating current. If directcurrent analogues are employed, a respective alternating cycle isinduced in winding 38 each time the winding passes a tooth 20 as shaft32 rotates. The magnitude of each signal is proportional to themagnitude of the input signal, the velocity of the rotating arm and theflux density underneath each tooth. If alternating current analogues areemployed, the voltages induced in winding 38 will appear as amplitudemodulated voltages. The amplitude of the envelope of each of theseoutput voltages is a maximum when portion 46 of arm 44 is directly overa winding 22. The envelope amplitude decreases to its minimum value asarm 44 leaves the magnetic field of the winding. The output signalmagnitude also depends on the speed of shaft 32 and the frequency of thealternating current analogue.

It will be understood that when a direct current or an alternatingcurrent analogue is employed, in each case the output signals havemagnitudes proportional to the respective magnitudes of the voltageanalogues.

The operation of the multiple form of my switch shown in FIGURE 3 issimilar to the operation of the form shown in FIGURES 1 and 2. In thiscase, however, owing to the staggered arrangement of the teeth 20 aplurality of respective signals proportional to the voltage analogues isproduced on conductors 70 and 72.

It will be seen that I have accomplished the objects of my invention. Ihave provided a rotary arm contactless switch for sequentially samplingrespective voltage analogues of a plurality of physical variables. In myswitch there is no direct physical engagement between the stationary andthe movable members. My switch does not include brushes and contacts ofthe type used in the prior art. It is extremely rugged and reliable inoperation. My switch requires very little maintenance even after a longperiod of time in use.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of myclaims. It is further obvious that various changes may be made indetails within the scope of my claims without departing from the spiritof my invention. It is, therefore, to be understood that my invention isnot to be limited to the specific details shown and described.

Having thus described my invention, What I claim is:

1. A contactless switch for sampling a plurality of voltage analogues ofrespective physical variables includ ing in combination a stationarysupport ring formed of diamagnetic material, a plurality of radiallyextending core teeth formed of magnetic material carried by said supportring, respective primary windings carried by said core teeth, a rotor,means mounting said rotor for movement about the axis of said ring, aradially extending core tooth formed of magnetic material carried bysaid rotor, a secondary winding carried by said rotor core tooth, saidrotor being adapted to be driven successively to align said rotor coretooth individually with each one of said stator core teeth, a radiallyextending arm formed of magnetic material and means mounting said arm onsaid rotor in spaced relation in the direction of said axis to saidrotor core for movement with said rotor, said arm extending to aposition adjacent and end of a stator tooth with which said rotor toothis aligned to complete a path for flux passing through said rotor coretooth and said aligned stator core tooth.

2. A contactless switch for sampling a plurality of voltage analogues ofrespective physical variables including in combination a stationarysupport ring formed of diamagnetic material, a plurality of radiallyextending core teeth formed of magnetic material carried by said supportring, respective primary windings carried by said core teeth, a rotor,means mounting said rotor for movement about the axis of said ring, aradially extending core tooth formed of magnetic material carried bysaid rotor, a secondary winding carried by said rotor core tooth, saidrotor being adapted to be driven successively to align said rotor coretooth individually with each each one of said stator core teeth, aradially extending arm formed of magnetic material and means mountingsaid arm on said rotor in spaced relation in the direction of said axisto said rotor core tooth for movement with said rotor, said armextending to a position adjacent an end of a stator tooth with whichsaid rotor tooth is aligned to complete a path for flux passing throughsaid rotor core tooth and said aligned stator core tooth and includingan offset portion extending in an axial direction over the end of saidaligned stator tooth.

3. A contactless switch for sequentially sampling re spective voltageanalogues of a plurality of physical variables including in combinationa stator formed of diamagnetic material, a plurality of respectivecoaxial rings of spaced radially extending teeth of magnetic materialcarried by said stator, the teeth of each ring being staggered withrespect to the remaining rings, respective primary windings carried bysaid teeth, means impressing the respective voltage analogues on saidprimary windings to produce magnetic fields in said teeth, a rotor,means mounting said rotor for movement about the axis of said rings, aplurality of radially extending rotor core teeth formed of magneticmaterial, means mounting said rotor teeth in axially spaced relationshipon said rotor for cooperation with the respective rings of stator coreteeth, respective secondary windings carried by said rotor core teeth,said rotor being adapted to be driven successively to align each of saidrotor teeth individually with the stator core teeth of the associatedring, respective radially extending arms formed of magnetic material,and means mounting each of said arms on said rotor in spaced relation inthe direction of said axis to a rotor core tooth for movement with saidrotor, each of said arms extending to a position adjacent an end of astator tooth with which the corresponding rotor tooth is aligned tocomplete a path for flux passing through the rotor core tooth with whichit is associated and said aligned stator core tooth.

References Cited in the file of this patent UNITED STATES PATENTS344,318 Jones June 22, 1886 739,572 Armstrong Sept. 22, 1903 1,984,939Nachumsohn Dec. 18, 1934 2,459,704 Johnson Jan. 18, 1949 2,786,182Herbert Mar. 19, 1957 2,807,756 Cronin Sept. 24, 1957 FOREIGN PATENTS21,680 Great Britain Sept. 23, 1915 of 1914

